pcprofile.c

/* Profile PC and write result to FIFO. Copyright (C) 1999, 2000 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */#include <errno.h>#include <fcntl.h>#include <stdint.h>#include <stdlib.h>#include <unistd.h>#include <libc-internal.h>/* Nonzero if we are actually doing something. */staticint active;
/* The file descriptor of the FIFO. */staticint fd;
staticvoid
__attribute__ ((constructor))
install (void)
{
/* See whether the environment variable `PCPROFILE_OUTPUT' is defined. If yes, it should name a FIFO. We open it and mark ourself as active. */constchar *outfile = getenv ("PCPROFILE_OUTPUT");
if (outfile != NULL && *outfile != '\0')
{
fd = open (outfile, O_RDWR | O_CREAT, 0666);
if (fd != -1)
{
uint32_t word;
active = 1;
/* Write a magic word which tells the reader about the byte order and the size of the following entries. */
word = 0xdeb00000 | sizeof (void *);
if (TEMP_FAILURE_RETRY (write (fd, &word, 4)) != 4)
{
/* If even this fails we shouldn't try further. */
close (fd);
fd = -1;
active = 0;
}
}
}
}
staticvoid
__attribute__ ((destructor))
uninstall (void)
{
if (active)
close (fd);
}
void
__cyg_profile_func_enter (void *this_fn, void *call_site)
{
void *buf[2];
if (! active)
return;
/* Now write out the current position and that of the caller. We do this now, and don't cache the because we want real-time output. */
buf[0] = this_fn;
buf[1] = call_site;
write (fd, buf, sizeof buf);
}
/* We don't handle entry and exit differently here. */
strong_alias (__cyg_profile_func_enter, __cyg_profile_func_exit)